Dont activate an address if another system has it active

app/Http/Controllers/SystemController.php

@@ -528,6 +528,18 @@ class SystemController extends Controller
 		$this->authorize('admin',$o);
 		session()->flash('accordion','address');
 
+		// Make sure that no other system has this address active.
+		if (! $o->active && ($x=Address::where([
+				'zone_id'=>$o->zone_id,
+				'host_id'=>$o->host_id,
+				'node_id'=>$o->node_id,
+				'point_id'=>$o->point_id,
+				'active'=>TRUE,
+			])->single())) {
+
+			return redirect()->back()->withErrors(['susaddress'=>sprintf('%s is already active on system [<a href="%s">%s</a>]',$o->ftn,url('ftn/system/addedit',$x->system_id),$x->system->name)]);
+		}
+
 		$o->active = (! $o->active);
 		$o->save();